Morphometric Analysis of Shell and Operculum Variations in the Viviparid Snail, Cipangopaludina chinensis (Mollusca: Gastropoda), in Taiwan

臺灣產中國圓田螺（軟體動物：腹足綱）之外殼及口蓋形質測量分析

邱郁文(Yuh-Wen Chiu) ； 陳弘成(Hon-Cheng Chen) ； 李信徹(Sin-Che Lee) ； 陳昭倫(Allen Chao-Lun Chen)

《Zoological Studies》 41卷3期 (2002/07) Pp. 321-331

摘要

中國圓田螺是廣布於亞洲地區的淡水螺，受相對成長與環境因子的影響，常造成種內殼形的變異。本研究以形質測量分析法判別產自包括竹子湖、老梅、蘭潭及萬大四個臺灣的族群，與韓國光州的一個族群之中國圓田螺外殼與口蓋形質的變異。以線性迴歸法分析發現中國圓田螺具有外殼異速成長的現象，依此排除外殼相對成長所產生的變異後，再以多元尺度分析和判別分析檢驗十三個外殼及口蓋的測量形質。由這兩種分析顯示，在五個族群中可區分出兩種形態型，分別為長塔型與短塔型。多元尺度分析將竹子湖和老梅兩短塔型族群分為形態相關的一群，而蘭潭、萬大和韓國光州為形態相關的長塔型。判別分析顯示螺塔高是貢獻於族群間判別函數中最主要的形態測量形質。線性迴歸法分析更進一步的指出，長塔型螺塔增長的速率顯著的比短塔型螺塔增長速率快。因此，螺塔高成長速率上的差別是造成中國圓田螺種內具有兩種形態型的主要原因。本文並討論造成兩種形態型相對成長的模式與環境因子間關係。

關鍵字

形質分析法 ； 田螺 ； 相對成長 ； 形態型

並列摘要

The viviparid snail, Cipangopaludina chinensis, is one of the widely distributed freshwater gastropods in Asia, whose intraspecific variations in shell morphology and operculum were thought to be due to ontogenetic allometric growth or environmental effects. In this study, morphometric analyses were applied to discriminate shell and operculum variations in 251 individuals of C. chinensis from 5 populations, including Chutzuhu, Laumay, Lantan, and Wanda in Taiwan, and 1, Kwangju, in Korea. The allometric shell growth pattern in C. chinensis was identified using linear regression analysis. Thirteen shell and operculum characters were measured and examined using multidimensional scaling (MDS) and canonical discriminate analysis (CDA). These 2 analyses clearly demonstrated that 2 morphotypes, namely a tall-spired form and a short-spired form, exist among the 5 populations. MDS indicated that snails with the shorter shell spire in Chutzuhu and Laumay were morphologically related. CDA suggested that spire height is the most important character contributing to variation between these populations. One of the factors causing variation in spire height within and between populations is allometric growth. Different growth rates between the spire and other portions of the shell result in the shell changing shape with growth. Linear regression demonstrated that the spire of the tall-spired form lengthens at a faster rate than that of the short-spired form. Different growth rates in the spire thus contributed to the major difference in shell shape between the 2 morphotypes. Ontogenetic allometric growth and environmental factors that contribute to the configuration of the 2 morphotypes in C. chinensis are discussed.

並列關鍵字

Morphometric analysis ； Viviparid snail ； Allometric growth ； Morphotype